The killings of 14 people in a California social service center’s banquet facility, with more injured and what police described as the killers’ apparent plan for a greater loss of life, have left the nation stunned.

In Vermont, a child protection social worker for the state of Vermont said the massacre in San Bernardino prompted memories of the loss of her coworker this summer.

"I just feel this overwhelming sadness," said Trissie Casanova, a Department for Children and Families social worker, in reference to the California violence. "It kind of just hit me in the pit of my stomach that this happened again."

This summer, Casanova's fellow DCF social worker, Lara Sobel, was the victim of a mass murder in central Vermont. She was the fourth victim, shot, allegedly by a rampaging parent angry she lost child custody. The other victims were three relatives of the suspect, Jody Herring.

"It's just really, really heartbreaking, and hard to understand why this happened," Casanova said of the kind of violence that could claim multiple victims.

Investigators in San Bernardino are still trying to understand what happened in Wednesday's massacre at an employee holiday banquet for the county health department.

The two attackers killed 14 people in a rampage at a banquet, fired as many as 75 rifle rounds at the scene, left behind three rigged-together pipe bombs with a remote-control device that apparently malfunctioned, and had over 1,600 more bullets with them when they were gunned down in their SUV, authorities said Thursday.

At their home, they had 12 pipe bombs, tools for making more explosives, and over 3,000 rounds of ammunition, Police Chief Jarrod Burguan said in a grim morning-after inventory that suggested Wednesday's bloodbath could have been far worse.

Wearing military-style gear and wielding assault rifles, Syed Rizwan Farook, a 28-year-old county restaurant inspector, and his wife, Tashfeen Malik, 27, slaughtered 14 and wounded 17 in the attack at a social service center shortly after he slipped away from an employee banquet he was attending there, the Associated Press reported.

The couple were shot to death about four hours later and a few miles away in a furious gunbattle with police, the AP wrote.

At the White House, President Barack Obama said after meeting with his national security team that it was "possible this was terrorist-related" but that authorities were unsure. He raised the possibility that it was a workplace dispute or that mixed motives were at play.

Law enforcement experts said investigators may well conclude the killers had more than one motivation.

"Typically, mass murderers don't randomly select their location in which they select their kills," said Penny Shtull, a criminologist at Norwich University in Northfield, Vermont who studies mass killings.

In cases possibly involving disgruntled workers, Shtull told necn anger over a perceived injustice can start murderers plotting, then they fester and continue their planning, until they get try to get their message known in an explosive way.

"They may select specific individuals they feel did them the most injustice and then anyone else is fair game," Shtull said of mass killings. "This is their way of getting revenge or payback; of getting their message known-- getting their 15 minutes of fame."

Shtull said an unusual element of the San Bernardino rampage was the fact a female appears to have participated in the killings. Shtull said men are more typically mass killers, and in cases where teams are involved, the teams are usually made up of men.

“Women very rarely tend to commit mass murders,” Shtull said. “If they do, their victims tend to be their families. Their children, for example.”

Shtull said she will be interested to learn more about the relationship between Farook and Malik, and if coercion, intimidation, or domestic violence may have been present in this case. “Clearly, we need to know more about the relationship between them,” Shtull added.

Shtull also said the home is where most mass killings take place in the United States, often involving family members and suicide.

Gov. Peter Shumlin, D-Vermont, expressed heartbreak Thursday over the violence, along with other recent mass killings in Colorado and in Paris.

Shumlin acknowledged the national conversation over gun control will be a passionate debate.

Casanova said the Vermont State Employees' Association has a memorial fund aimed at helping Lara Sobel's children, Julia and Elahna. That effort is aimed at providing for future health, welfare, and educational needs for the girls, according to the union's website.

Click here for more information on the VSEA's efforts to raise money to support Sobel's daughters: VSEA